Electric incandescent lamp.



No. 817,732. PATENTED APR. 10, 1906. w. VON BOLTON. ELECTRIC INOA'NDESOENT LAMP.

APPLICATION FILED DEC. 28, 1905.

WITNESSES 4 I v 1- T R- 1 W 3 age v UNITED sfrn rns PATENT OFFICE. V

WVERNER VON BOLTON, OF GHARLO'I"ENBURG, GERMANY, ASSIG-NOR TO SIEMENS & HALSKE kKIIENGESELLSGHAFT, OF BERLIN, GERMANY;

ELECTRIC INCANDIESCVENT LAMP.

Specification of Letters atent.

Patented April 10, 1906.

Original application filed May 31, 1902, Serial No. 109,793. Dividedand this application filed December 28 1905. Serial No.293,6l6,

To all 1071,0111 it may concern/i I 7 Be 1t known that I, WER ER VON BOLTON, chemist, a sub e.ct of the Russian Emperor,

residing at 10, Am Liitzow, Charlottenburg,v

nearBerlin, Germany, have invented certain new and u useful Improvements in Electric Incandescent Lamps; and I do hereby dee Clare the following to be a full, clear, and e x act description of the invention, such as will enable vot lers' skilled in the art to which it appertains to make and use the same.

My invention relatesto improvements in incandescing bodies for electric low -lam s, and in particular tometalhc fiIaments or, such glow-la mps.

The object of my invention is tofprovide an mcandescing body for electric glow-lamps whlch will have a high hght-emittmg-efii ciency, will give. a light of color suitable and pleasing for illuminatingpurposes, will be sufficiently durable to meet commercial re-, quirements, and 'whichxcan be manufactured at a reasonable cost.

With this object in view m T invention con sists in an incandescing body or electric glowlamps iormed of one of the metals of the vanadium groupfo.r example, substantially pure metallic tantalum. I use the term substantially'pure metallic tantalum to distinguish the material employed by me from' a material which has heretofore been known and called metallic tantalum, but

which, as a matter of fact, was always combined either chemically or in the form of an alloy with some other materialsas, for example, the alloy of tantalum with hydrogen.

The properties of the substantially pure metallic tantalum are radically different from the material hitherto known and supposed to be metallic tantalum. l/Vhile the material hitherto known was said to be brittle and could not be wrought, substantially pure metallic tantalum is exceedingly ductile and can be wroughtthat is to say, welded, rolled, hammered, and drawn-in other words, manipulated in' a manner which differentiates it essentially from the material hitherto known and supposed. to be metallic tantalum. Thus from the material employed by me a wrought filament may be produced, while from the material hitherto known the production of such a filament Was an impossibility.

of the many forms in ,which my invention forme I have discovered that substantially pure I metallic tantalum has properties Which-spec1ally adapt it for use as a descent lamps.

A filament oi -substantially pure metallic tantalum has a light-emitting efiiciency far superior to the carbon filament now in general use and gives a light which, whilevery brilliant, is not. marked by any disagreeable color, but, on the contrary, is very satisfactory for purposes of illumination. Moreover, .such a filament is homogeneous and.

's'ufiiciently durable to meet all commercial of'manufacturing. it. In order, however, to

comply with the statute, I will nowdescribe 7m a general way the Vmanner of. producing my new filament. v I

In the accompanying trated a'glow-lamp having a filament in one may be em loyed, it being assumed that the particular la'mentillustrated is composed of substantially pure tantalum metal.

I-have illus- In orderto first obtain a coherent-metallic body of tantalum, I mix the amorphous powtier of' tantalum metal (in whichiorm the'im "pure metal commonly occurs) with suitable inding substanceswhich rnay be volatiley and I have found that paraffin is a good'and' useful binding substance for this purpose, The resulting plastic mass may be pressed so as to take the shape whichwill be the most convenient for further treatment. I have also found by experiments that the amorphous powder or tantalum metal can be transinto a coherent body by very high pressure, so that no binding substance is nec-. essary. I obtain a more or less strong and co ierent metallic body, 1 I prefer to avoid the useo'r binding substances in forming the body and to condense the amorphous powder merely by sufiicient pressure. 1 If organic bin-ding substances, such as par- According to the pressure em loyed V afiin, are used, the resulting body is placed in Y 55 glower forincam I V Under the influence of theheat fiibateea by the electric cu'r entfinally a sintered or; molten homogeneous metalhc bod is ob tained, which can be hammered or orged or rolled or drawn to Wire or treated any known mechanical Way. I prefer to reduce the homogeneous metallic body obtainedin the above-described manner .to' rods" or the like of suitable'cross-section by'pressing roll lamps, consisting of a orawn wire of metallic ing, or the like and their todraw wires" from said rods.

The incandescent bodies obtained accordto my said invention by either of the above-explained modifications of my process may be employed in the usual Way in a glass 31, 1902, of which this present application is a division. r I a witnesses.

lamps, consisting of a wrought metal of the vanadium group.

3. An incandescing body for electric glowlamps,'consisting of a Wrought filament of 'metallic' tantalum.

i 4. Anincandescing body for electric glowtantalum. r

5. Al filament ior use as aglower for an incandescent electric lamp, composed of ductile tantalum.

I 6.; incandescing body ,for'electric glowlampsfcons'istin'g of a homogeneous metallic Wrought filament of tantalum.

In' testimony whereoi I affix my signature to this specification 1n the-presence 01 two WERNER VON BOLTON.

-Witnesses: V

' .HENRX Hnsr'nn,

1 WOLDEMAR HAUrT. 

